Safety device for baling-presses



C. R. LITTIG, SAFETY DEVICE FOR BALING PRESSES'.

APPLICATION FILED WIT-1211917.

Patented Sept. 21, 1920.

, a citizen of the United States,

UNITED STATES PATENT OFFICE.

SAFETY DEVICE FOR BALING-PRESSES.

Specification of Letters Iatcnt.

Patented Sept. 21, 1920.

Application filed October 12, 1917. Serial No. 196,127.

To all whom it may concern Be it known that 1, CHARLES Ross LITTIG, residing at Chicago, in the county of Cook and State of Illinois, have invented a certain new and useful Improvement in Safety Devices for Baling-Presses, of which the following is a full, clear, concise, and exact description.

My invention relates to improvements in safety devices for baling presses.

'The object of'the invention is to provide a device of this character which may be relied on to prevent damage to the machine regardless ofthe degree of care exercised by the operator.

Where presses are employed to compress material for various purposes, as for example, where said material is to/be made into bales, it is desirable to provide an overload device which shall automatically stop the machine when the material has been compressed to such a degree that further compression would result in imposing excessive stresses on the machine and possibly damage it. Where-such machines have been driven by electric motors, it has been proposed heretofore to provide an overload re lease switch to stop the motor when an abnormal load is imposed thereon due to the fact that the material has been compressed as much as is practical. Such overload release switches, however, are frequently caused to operate .by the heavy current sup lied to the motor in starting the machine. 0 prevent such premature operation of the overload release switch, variousdevices have been employed, such as a mechincal lock on the switch contacts released after a predetermined movement of a dash pot. In such cases the said overload release switch its controlled by a time element. This arrangement has proved inadequate under certain conditions such as obtained if the operator starts the machine and permits the compression to continue until the overload release switch stops the motor after which the operator may start the motor again to further compress the material. Under these circumstances the overload release switch would be held closed for a certain interval of time, when it should be inoperative, resulting in damage to the apparatus.

I overcome this" difiiculty by providing ment of an abnormal load.

Referring to the drawings Figure 1 is a circuit diagram, and

Fig. 2 is a simplified showing of a baling press.

The invention is shown as applied to and embodied as a part of a paper baling press although it is not limited to this particular 7 use. The press which has beenselected for purposes of illustration consists of a suitable base 1, a frame consisting of uprights 22 and a top 3. The paper is compressed between the base 1 and a movable platen 4 which is moved downwardly by means of a toggle consisting of links 5-5 and suitable accessories which need not be described in detail herein. The upper ends of the toggle are caused to move toward each other by a screw-threaded rod 6 which is driven through'a chain of reduction gearing 7 by an electric motor 8. A manually operated switch is mounted on the machine in some convenient position in a suitable container 9 and an electromagnetic switch is mounted in a suitable container 9.

The electric motor in the present instance is one adapted to operate on a three phase circuit 101112. To start the motor a manual switch 13 is operated thereby bridging contacts 14-14 and permitting current to flow from one of the mains 10 through the conductors 1516 connected to said switch thereby supplying current to the closing coil 17 of the electromagnetic switch previously mentioned, the return circuit being through the return conductor 18, overload limit switch 19, down limit switch 20, the auxiliary contact 21, and conductor 22 to the main 12.

When the coil 17 is energized, the motor circuit is closed through the switch contacts 2324 thereby supplying current to the motor armature 25 through the conductor 26 on one hand and through the overload release coil 27 to the switch blade 28 and conductor 29 on the other hand. The third leg of the armature circuit is established through the conductor 30, switch contact 31,

and conductor 22 back to the main 12. As

soon as the electromagnetic switch closes, 5 the circuit to the-holding coil 17 is established by the auxiliary contact 32 and conductor 33 so that the switch remains closed after the manually operated switch 13 is released. The rush of starting current through the overload release coil 27 causes the contact 34 to open the circuit between the two contacts 3535 which is normally bridged thereby. However, the circuit ,of the starting coil 17 remains closed through the overload limit switch 19 which latter constitutes a short circuit around the switch 34.- After the motor has started the circuit is also established by the switch 34. After the platen has moved downwardly a prederoller 37 thereby opening the said overload limit switch 19. The said switch may be of any suitable construction and may be located in any convenient part of the machine and arranged to be opened after a predetermined movement of some movable part. 1

As the platen 4 descends, the material being. compressed thereunder increases the stresses on the machine. In order to limit these stresses'and prevent breakage of the machine, the overload coil 27 is so designed as to cause the motor circuit to be opened when a predetermined maximum limit has been reached. This coil 27 is operated by the increased flow of current to the motor due to the increased load. When the circuit is opened by the contacts 349-35, the closing coil 17 will be 'deenergized, permitting the electromagnetic switch contacts 23-24 to open the motor circuit. 1

When only a small quantity of material is put in the press, it somet imes happens that the load thrown on the motor is not sufficient to operate the overload release switch. -In order to prevent damage to the mechanism due to the continuous operation of the motor, I provide a down limit switch 20 which is opened liy a shoe 38 thereby stopping the motor. also provide an up- 'per limit switch 39 which is also opened by said shoe when the platen 4 is in uppermost position. This. switch prevents breakage which would be caused by the continuedupward movement of the platen 4 after the operator has thrown the switch handle 40 of the reversin switch to uppermost position, Fig. '1. 'en the motor is reversed to lift the platen, the down limit switch 20 is opened and the up limit switch 39 is closed.

The overload limit switch 19 is also open.

Under these circumstances, the motor would stop when the overload release coil 27 is op termined distancethe shoe 36 engages a limit switch 39 and conductor 41. The positioning of the various limit switches with reference to shoes 36, 38 is such that the short circuit controlled by the overload switch is always closed when the platen is in uppermost position and} the motor about to start. The overload limit switch is opened after the platen has completed one fourth of its downward movement and is thereafter held open throughout said downward movement. It is obvious that this timing may be varied to meet difierent requirements and furthermore, the various limit switches and shoes may be located on other parts of the machine.

It will thus be seen that the machine is protected against damage regardless of lack of care on the partof the operator. In addition to the above features, it will also be noted that when the electromagnetic switch opens, the circuit of the closing coil 17 is also opened by the auxiliary contact 32. This arrangement prevents the reclosing of said electromagnetic switch when the overload switch drops, as it does as soon as the 0 armature circuit is opened.

.Itwill be apparent that the electrical features of the invention are independent of the particular machine to which they are shown applied in the present instance and furthermore various parts may be used independently of others. I, therefore, do not desire to limit myself to the embodiment of the invention illustrated and described herein except where limitations are imposed in the applended claims. 1

' aving thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is: r

1. n combination, a motor, an overload swi h; a reversing switch-having two circuit closing positions, alimit switch v arranged to operate only when said reversing switch is in one position, a second limit switch arranged to operate only when said 11 reversing switch is in the other position and an additional limit switch controlling the operation of said overload switch.

2. In combination, a three phase electric motor having an armature, a source of three phase current therefor, an electromagnetic switch cpntrolling the current supplied to said armature from said source, a reversing switch connected in circuit with said armature, a starting switch and an overload switch connected in circuit with said arms for preventing intermittent operation of ture, a starting switch and an overload said magnetic switch after said overload switch in the armature circuit between said switch operates. 10 electromagnetic switch and said reversing In witness whereof, I hereunto subscribe switch, an overload limit switch short cirmy name this 10th day of October A. D.v cuiting said overload switch during the 1917.

period when the motor is starting, and means CHARLES ROSS LITTIG. 

